1. Field of the Invention
This invention relates to shift lever assemblies for operating automatic transmissions used in vehicles.
2. Description of the Prior Art
FIG. 11 shows an example of prior art shift lever assembly for operating an automatic transmission in sectional view. As shown, the shift lever assembly comprises a lever body 180 having a lever shaft 182 and a lever knob 186. The lever knob 186 is coupled to the upper end of the lever shaft 182. The lever shaft 182 has its lower end supported by a support shaft 188 on a lever support 190 such that the lever body 180 can be turned about the support shaft 188 in directions of shifting operation. The shift position of the lever body 180 can be seen by observing a shift position indication panel 192 which is secured to the lever support 190. The shift position indication panel 192 has an opening 194 through which the lever body 180 can be shifted.
The opening 194 of the shift position indication panel 192 is elongate in shape, covering the range of shifting of the lever body 180. The width of the opening 194, however, is smaller than the width of the lever knob 186. Therefore, when assembling the shift lever assembly, the lever shaft 182 is first mounted by the support shaft 188 on the lever support 190 before mounting the lever knob 186 thereon. Then, the lever shaft 182 is passed through the opening 194 of the shift position indication panel 192, which is then mounted on the lever support 190. Subsequently, the lever knob 186 is secured by screws (not shown) to a metal pipe 184 which is inserted in the lever shaft 182.
In this way, the lever body 180 requires coupling of the lever shaft 182 and the lever knob 186 fabricated as separate parts by means of screws. This means that the insert position of the metal pipe 184 in the lever shaft 182 and the coupling position of the lever knob 186 with respect to the metal pipe 184 may fluctuate. These fluctuations tend to deteriorate the positioning accuracy of the lever knob 186. In addition, since the assembling of the lever assembly requires a step of coupling the lever shaft 182 and the lever knob 186, the productivity of the assembly is correspondingly reduced.
The opening 194 of the shift position indication panel 192 is covered by a slide cover 130 shown in FIG. 12, and a shift position indicator 132 is provided on one side of the slide cover 130. As shown in FIG. 12, the shift position indicator 132 provided on one side of the slide cover 130, has a rectangular position indication tape accommodation member 132a having three, low level side walls 134 to 136. A rectangular position indication tape 140 is accommodated in and applied to the accommodation member 132a. The position indication tape 140 usually consists of a red fluorescent adhesive tape.
By a shifting operation of the lever body 180, the shift position indicator 132 is caused to move along the underside of a shift position indication panel 192, as shown in FIG. 13. The shift position indication panel 192 further has openings or windows 117 formed at its positions corresponding to respective shift positions of the lever body 180. At each shift position, the shift position indicator 132 is found right underneath the corresponding window 117.
As best shown in FIG. 13, when the shift position indicator 132 is looked at from driver's eye point 150 through the window 117, an edge 140a of the position indication tape 140 is seen as exposed. Meanwhile, the position indication tape 140 is applied manually to the position indication tape accommodation member 132a, and it is considerably difficult to secure a given positioning accuracy of the application of the position indication tape 140.
Deviations of the application position of the position indication tape 140 with respect to the position indication tape accommodation member 132a, are undesired from the standpoint of ready confirmation of the indication. It is therefore necessary to apply the position indication tape 140 very carefully. This leads to reduced operability.
FIG. 14 is a sectional view showing the prior art shift lever assembly for automatic transmission. For the purpose of closing the opening 194 of the shift position indication panel 192, the slide cover 130, which is made of a soft resin and which has a strip-like shape, is mounted such that it is moved along an arcuate design curve of the shift position indication panel 192 in an interlocked relation to the shifting operation of the lever body 180.
For the movement of the slide cover 130 of a soft resin along the curved line of the shift position indication panel 192 in response to the shifting operation of the lever body 180, it is necessary to guide the slide cover 130 with a guide groove and other position regulation members provided along the opening 194 of the shift position indication panel 192. This complicates the shape of the lever support 190, thus leading to increased cost of manufacture. Further, to permit displacement of the slide cover 130 relative to the lever body 180 in the axial direction thereof at the time of shifting operation, the lever body 180 is inserted with a play through a hole formed in the slide cover 130.
Thus, when the lever body 180 is moved in tile shifting operation, the slide cover 130 receives frictional resistance and is displaced relative to the lever body 180. As a result, a deviation is produced between the shift position of the lever body 180 and the position of the shift position indicator 132, thus resulting in inaccurate shift position indication.
Moreover, it is required to provide guide groove and other position restriction means for the shift position indication panel 192 and also form the slide cover 130 from a resin material which is soft, wear-resistant and hence expensive, thus leading to increased cost.
In FIGS. 15 to 17, a shift lock mechanism of the prior art shift lever assembly is shown. FIG. 15 is a plan view showing the shift lever assembly. FIG. 16 is a plan view showing the internal construction of the assembly. FIG. 17 is a side sectional view showing the assembly.
In the lever body 180 noted above, a detent rod 160 is assembled for axial displacement. A detent pin 161 is secured to a lower portion of the detent rod 160 such that it penetrates an opening of the lever body 180 to the outside. By depressing a knob button (not shown) provided on the lever knob 186 at the upper end of the lever body 180, the detent rod 160 is displaced downward against the biasing force of a return spring.
The detent pin 161 is found in a detent groove 114 formed in the lever support 190. The biasing force of the return spring acting on the detent rod 160 normally holds the detent pin 161 to be in an upper edge recess of the detent groove 114. The detent rod 160, detent pin 161, detent groove 114 and related parts constitute a detent mechanism.
In the shift lever assembly, for executing an operation of shifting the lever body 180 from a parking position P to, for instance, a reverse position R which is one of running speed positions, or executing a reverse shifting operation, the detent rod 160 is displaced downward by depressing the knob button (not shown). As a result, the lock by the detent mechanism is released, thus making it possible to shift the lever body 180 for a shifting operation.
Now, a shift lock mechanism for locking the detent pin 161 against downward displacement when the lever body 180 is in the parking range P, will be described.
A lock plate 199 is provided for vertical movement on the lever support 190. The lock plate 199 has a locking recess 191 in which the detent pin 161 can be received when the lever body 180 is shifted from the reverse position R to the parking position P. FIG. 17 shows a state of the shift lever assembly in which the detent pin 161 is received in the locking recess 191 and the lock plate 199 is held in a position raised by the return spring acting on the detent rod 160.
Meanwhile, a shaft 196 having a pair of, i.e., right and left, lock levers 195 is rotatably supported on the lever support 190. In the state shown in FIG. 17, one of the lock levers 195 has its upper end lock portion 197 found in a notch 192 formed in the lock plate 199. This state corresponds to a lock state of the detent mechanism. In this state, if it is intended to cause downward displacement of the lock plate 199, the notch 192 strikes the lock portion 197 of the lock lever 195, thus blocking further downward displacement.
The lever support 190 further supports a solenoid 170 which is an electric actuator. The solenoid 170 is controlled by a control computer (not numbered). When the brake pedal of a vehicle is depressed with the lever body 180 in the parking position, the solenoid 170 is energized to pull a plunger 172. When the brake pedal is released, it is de-energized.
A solenoid rod 181 is coupled to the plunger 172 of the solenoid 170. Between the solenoid rod 181 and solenoid 170, a spring 175 is provided to bias the solenoid rod 181 in an advancing direction.
The lock lever 195 is rotatably coupled by a pin 187 to the other lock lever 195. The solenoid rod 180 has an inclined cam face 185. Facing the cam face 185 is an inclined cam face (not numbered) formed at the lower end of an operating rod 151 of a lock release button 150 which is assembled for vertical displacement on the lever support 190. The solenoid 181 thus can be retreated (i.e., moved to the left in FIG. 17) against the biasing force of the spring 175 by manually pushing down the lock release button 150.
In this shift lock mechanism, when the brake pedal is not depressed with the lever body 180 in the parking position P, if it is intended to push down the detent rod 160, the downward displacement of the interlocked lock plate 199 is blocked by the engagement between the notch 192 and the lock portion 197 of the lock lever 195. Thus, the lock of the detent mechanism can not be released, and hence the lever body 180 can not be shifted from the parking position P to a different position.
When the brake pedal is depressed in this state, the solenoid 170 is energized, causing the solenoid rod 181 to be retreated together with the plunger 172 against the biasing force of the spring 175. Thus, the lock lever 195 is retreated to a position shown by phantom line in FIG. 17, thus bringing about a lock release state. The lock release may also be realized by manually pushing down the lock release button 150.
In the lock release state, the detent rod 160 can be displaced downward for shifting the lever body 180 from the parking position to a different position.
The lever body 180 having been shifted to a different position from the parking position, can be shifted back to the parking position with the detent rod 160 held displaced downward. When the detent pin 161 is restored upward in its state of engagement in the locking recess 191 of the lock plate 199, the shift lock mechanism is again brought to the lock state.
In the prior art shift lock mechanism as described, many intermediate parts such as the solenoid rod 181, lock lever 195 and lock plate 199 are provided between the solenoid 170 and the detent rod 160. The necessity of these intermediate members stems from the construction for blocking the downward displacement of the detent pin 161 of the detent rod 160.
Problems posed by the presence of many intermediate parts are as follows.
(1) The construction is complicated. PA1 (2) It is difficult to realize a compact construction. PA1 (3) Cost is increased. PA1 (4) The productivity is low. PA1 (5) The shift lock range is readily subject to fluctuations, and it is difficult to ensure a given shift lock range accuracy. PA1 (6) The coupling portions of the intermediate parts are subject to great frictional resistances. Therefore, the operability is low, and the feel of manually pushing down the lock release button is reduced.